Way´s Steam Towboat Directory lists two towboats called Duffy:
Sternwheel towboat wh 1909-1920?, buildt in Marietta, Oh, 118.1*24.8*4. Owned by the Duffy coal and sand firm in Louisville, KY.
Sternwheel towboat sh 1921-1946, buildt in Jeffersonville, IN by Howard, 125*25*4.6. Engines 14 1/2´s-4 172 ft. stroke from former packet E. G. RAGON. Owned by the Ohio River Sand & Gravel Co., Louisville. Capt. William Daugherty was master of her near as long as she ran. William Heyn was chief engineer and had been on boath DUFFY boats (died at Jeffersonville, IN September, 1935). Charles R. Harding, Jr. was engineer on her 1921-1937. Capt. Daugherty was transferred to the new diesel J. H. DUFFY in 1938 but was temporarily back on the steamboat DUFFY when he fell overboard. His body was found on November 21, 1939 above 12 Mile Island, upriver from Louisville. Another crew member, John Brendel, also missing, was located next day by USCG. Capt. Wymond Brasher then went on her; James C. Thacker was chief engineer. This boat was dismantled in July, 1946 and was towed to Cincinnati where Capt. John L. Beatty wrecked her.
So the second DUFFY is yours. The Towboat Directory can still be purchased via Amazon.com (have a look on our book list).
For photos maybe the collection of Ralph DuPae, LaCrosse, WI can help you (University of La Crosse).